Extended-Distance Ports; High-Availability Considerations - McDATA StorageWorks 2/140 - Director Switch Planning Manual

Physical Planning Considerations
5
Extended-Distance
Ports
High-Availability
Considerations
McDATA Products in a SAN Environment - Planning Manual
5-6
• Existing cable restrictions - The enterprise may contain only one
type of fiber-optic cable (multimode or singlemode), and the
customer may be required to use the existing cables. Customers
may also be required to use existing copper cables for some
arbitrated loop devices.
Through longwave laser transceivers and repeaters or wavelength
division multiplexing (WDM) equipment, directors and fabric
switches support Fibre Channel data transmission distances of over
100 km. The extended distance feature is enabled on a port-by-port
basis by using entries in the RX BB Credit column for a specified port
at the Element Manager application's Configure Ports dialog box. This
feature provides extended distance support using Fibre Channel
protocol. Refer to Distance Extension Through BB_Credit
information.
When a director or fabric switch port is configured to support
extended link distances, the attached device (or attached fabric
element) must also support extended distance operation and be
configured to use a higher BB_Credit value to maintain link
efficiency. If the extended distance feature is enabled for a port that is
not installed or does not support extended distance operation, the
configuration for the feature is ignored.
To provide high device availability, critical servers, storage devices,
or applications should be connected to more than one fabric element
(director or switch) or to more than one fabric. To determine if
dual-connection capability exists for a device, refer to the associated
device documentation. To provide high fabric availability, consider
the use of multiple fabric elements (directors and switches), multiple
ISLs, or redundant fabrics. Refer to
Plan to maintain unused (spare) director and switch ports if port
connections must be quickly moved and re-established after a failure.
If an individual port or an entire port card fails, optical transceivers
or port cards can be removed and replaced, spare port connections
identified (through the Element Manager application), and fiber-optic
cables rerouted and reconnected while the director or switch is
operational.
for additional
Fabric Availability for information.